Chapter - 6
TISSUE
WHAT IS A TISSUE?
A GROUP OF CELLS THAT IS SPECIFICALLY FUNCTION ON A PARTICULAR PART OF BODY. THEREFORE, EVERY PART HAS ITS OWN TISSUE, TISSUES MIGHT VARY.
TISSUE IS ARRANGED AND DESIGNED SO AS TO GIVE THE HIGHEST POSSIBLE EFFICIENCY OF FUNCTION.
BLOOD AND PHLOEM ARE SOME EXAMPLES OF A TISSUE.
HOW IS IT CONNECTED?
CELLS = BASIC UNIT OF LIFE
Cells came together to form tissue.
Tissues came together to form ORGANS
ORGANS came together to form SYSTEM.
SYSTEM came together to form A HUMAN BODY/ ORGANISM.
A BRIEF EXPLANATION :
Since, We know that all living organism are made of cells
Most of these cells are specialised to carry out specific functions, each specialised function is take up by a different group of cells.
In Plants, vascular tissue conduct food ann water from one-part of plant to another parts. So multicellular organism show division of labour. Cells specialising in one function are often grouped together in the body.This means that a particular function is carried out by a cluster of cells, called tissue.
ANOTHER EXPLANATION -> A group of cells that are similar in structure and/or work together to achieve a particular function forms a tissue.
DO PLANTS AND ANIMALS HAVESAME TISSUES?
PLANTS AND ANIMALS DO NOT SHARE/HAVE THE SAME TISSUES.
They are very different ; following are some reasons why do aren’t made up of the same tissues.
SUPPORTIVE TISSUES ARE GENERALLY HAVE DEAD CELLS
Animals whereas move around in search of food etc. They consume more energy as compared to plant. So THERE MOST OF THE TISSUES ARE LIVING.
PLANT TISSUE ;
MERISTEMATIC TISSUE
The meristem is a type of tissue found in plants. It consists of undifferentiated cells capable of cell division. Cells in the meristem can develop into all the other tissues and organs that occur in plants. These cells continue to divide until a time when they get differentiated and then lose the ability to divide.
The meristematic tissue is further divided into APICAL, LATERAL and INTERCALARY, these are based on their location on the plant.
New cells produced by meristem are intially like those of meristem itself, but as hey grow and matre, their characteristics slowly change change and become differentiated as components of other tissue.
LOCATION OF MERISTEMATIC TISSUE IN PLANT BODY.
APICAL MERISTEM -> They are present at the growing tips of stem and roots and increases the length of the stem and the root. The girth (Width or Thickness) of the stem or root increase due to lateral meristem (called cambium)
LATERAL MERISTEM -> They are found in all woody plants and in some herbaceous ones, consist of the vascular cambium and the cork cambium. They produce secondary tissuesfrom a ring of vascular cambium in stems and roots.
INTERCALARY MERISTEM -> They are seen in some plants is located near the node.
PERMANENT TISSUE
Tissues that have become mature and do not have the ability to divide further are called permanent tissues. Permanent tissues are made up of cells that do not undergo cell division. The cells in these tissues are modified to perform some specific functions. Permanent tissues are derived from the meristematic tissue.
The process of taking up a permanent shape, size are called differentiation.
SIMPLE PERMANENT TISSUE :
The simple permanent tissues are made of similar cells performing similar functions. These are the basic packaging tissues in the plants.
The simple permanent tissues are the simple tissues. These are made of only one kind of cells. Explanation: As the cells that male up the tissues are the same they have the same structure and same type of parts. These can be classified into three main types named as Collenchyma, Parenchyma and Sclerenchyma,
-> The flexibility in plants is due to another permanent tissue, collenchyma. It allows bedding of various parts of a plant like tendrils and stem of climbers without breaking. It provides mechanical support
-> Parenchyma tissue is composed of thin-walled cells and makes up the photosynthetic tissue in leaves, the pulp of fruits, and the endosperm of many seeds. ... Unlike collenchyma, mature cells of this tissue are generally dead and have thick walls containing lignin. Their size, shape, and structure vary greatly.
-> Some cells of this tissue are living, elongated and irregularly thickened at the corners. This is very little intercellular space. Yet, another type of permanent tissue is called Sclerenchyma. It is made of SCLERENCHYMATOUS tissue. It is the tissue which makes the plant hard and stiff. The cells of this tissue are Dead.
COMPLEX PERMANENT TISSUE :
Complex permanent tissue is defined as a collection of structurally dissimilar cells performing a common function or set of functions. They are made up of more than one type of cells. They are of two types xylem and phloem. ... Phloem is the chief food carrying tissue of the plants.
Complex tissues are made of more than one type of cell. All these cell coordinate to perform a common function. Xylem and Phloem are examples of such tissues. They are both conducting tissues and constitute a vascular bundle.
VASCULAR TISSUE is a distinctive features of the complex plants, one that has made possible their survival the terrestrial environment.
ANIMAL TISSUE ;
The tissues of multicellular, complex animals are four primary types: epithelial, connective, muscle, and nervous. Recall that tissues are groups of similar cells group of similar cells carrying out related functions.
Epithelial Tissue -> Epithelial tissues are widespread throughout the body. They form the covering of all body surfaces, line body cavities and hollow organs, and are the major tissue in glands. They perform a variety of functions that include protection, secretion, absorption, excretion, filtration, diffusion, and sensory reception
Connective Tissue -> The connective tissues include several types of fibrous tissue that vary only in their density and cellularity, as well as the more specialized and recognizable variants—bone, ligaments, tendons, cartilage, and adipose (fat) tissue. .
Muscular Tissue -> Muscle tissue is composed of cells that have the special ability to shorten or contract in order to produce movement of the body parts. ... Actin and myosin are contractile proteins in muscle tissue. Muscle tissue can be categorized into skeletal muscle tissue, smooth muscle tissue, and cardiac muscle tissue.
Nervous Tissue -> Nervous tissue is found in the brain, spinal cord, and nerves. It is responsible for coordinating and controlling many body activities. ... The cells in nervous tissue that generate and conduct impulses are called neurons or nerve cells. These cells have three principal parts: the dendrites, the cell body, and one axon.